mainboard: Drop unnecessary VGA_BIOS default

This option defaults to n already.

Change-Id: I9f6407152f7cf2e2ac6fd1fff874e400f89a27ae
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/51339
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

src/mainboard/lippert/frontrunner-af/Kconfig

@@ -55,10 +55,6 @@ config ONBOARD_VGA_IS_PRIMARY
 	bool
 	default y
 
-config VGA_BIOS
-	bool
-	default n
-
 config VGA_BIOS_ID
 	string
 	default "1002,9802"